The present invention relates to a detection arrangement for detecting a state of wear of a chopping assembly of a forage harvester intended for processing a crop stream to a chopping assembly, and to a forage harvester.
The forage harvester under discussion is equipped with a chopping assembly which comprises a cutting cylinder including elongate chopping blades situated thereon, and comprises a stationary shear bar. The crop fed to the cutting cylinder is chopped, i.e., shredded, by way of the interaction between the chopping blades and the shear bar.
During the chopping operation, the chopping assembly undergoes wear which results from wear of the chopping blades. Specifically, a wear-induced removal of material occurs in the region of the cutting edges of the chopping blades, which results in a reduction in cutting quality and crop throughput.
The wear in the region of the cutting edges of the chopping blades results, on the one hand, in a change in the cutting-edge geometry and, on the other hand, in an enlargement of the engagement gap between the cutting edge and the shear bar. The cutting edge geometry can be restored only by sharpening the chopping blades, while the engagement gap between the cutting edge and the shear bar can be regularly adjusted by advancing the shear bar. In present-day forage harvesters, the two measures can take place automatically and without a visit to a repair facility, although the two measures must be initiated at the correct point in time. In this regard, the exact detection of the state of wear of the chopping assembly takes on particular significance.
The known detection arrangement for detecting a state of wear of a chopping assembly (DE 10 2014 218 408 A1), from which the invention proceeds, is based on the basic consideration that the engagement gap between the chopping blades and the shear bar can form a gap of a magnetic circuit, and therefore the state of wear of the particular chopping blade can be deduced from the change in the magnetic flux. For this purpose, the detection arrangement is equipped with a magnet arrangement which comprises a magnetic excitation arrangement in the form of a permanent magnet, and comprises a flux-conducting device for conducting a resultant magnetic flux.
When a chopping blade moves past the magnet arrangement, the magnet arrangement generates a magnetic flux which passes through the particular chopping blade transversely to the longitudinal extension thereof. The resultant magnetic flux depends, inter alia, on the state of wear of the particular chopping blade, and therefore, the state of wear can be deduced therefrom, in principle.
The known detection arrangement is disadvantageous in that the detection of the state of wear relates only to a single measurement point along the longitudinal extension of the particular chopping blade. This can result in a miscalculation of the state of wear, for example when a singular flaw of the chopping blade is present precisely at this measurement point, but the rest of the chopping blade is free from wear. In order to avoid such a miscalculation, several of the chopping blades moving past the magnet arrangement would have to be situated along the known detection arrangement. This would be disadvantageous in terms of cost.